A wireless communication network covers a certain geographic area by dividing the area into radio cells and each radio cell can be further divided into two or more sectors. Base stations, conceptually located at the center of respective cells/sectors, transmit information to a mobile communication device, also known as user equipment (UE), via downlink (DL) radio signals. Mobile communication devices transmit information to their serving base stations via uplink (UL) radio signals. A wireless communication network can be configured based on one of the number of wireless technology platforms, such as IS-95, CDMA2000 1×, EV-DO, UMB, GSM, WCDMA, HSPA (High-Speed Packet Access), LTE, WiMAX and WiFi wireless networks.
A real-time service, such as Voice over LTE (VoLTE), provides a carrier grade Voice over IP (VoIP) solution, built on an IP-Multimedia Sub System (IMS) architecture. In some applications, a native VoLTE client can be integrated into a design of a mobile communication device. Alternatively or in addition, a non-native VoLTE client can be provided by a third party and run on top of an application processor of the mobile communication device. Other general VoIP applications, such as Skype or Viber, sometimes referred to as over-the-top (OTT) VoIP applications, can also work over LTE radio, but generally without QoS support.
VoIP traffic is especially sensitive to modest network latency or packet loss, which can cause serious interruptions in a VoIP conversation. Accordingly, deployment of VoLTE requires a number of optimization steps to gain the full benefit of the technology's potential. Preferably, a success rate and retainability of a VoLTE call should match and exceed the level provided by circuit-switched connections.
Examples of key performance indicators (KPIs) in the radio network include setup success rate, handover success rate and call completion success rate. Network optimization includes parameter optimization and feature activation, such as header compression, Transmission Time Interval (TTI) bundling and QoS. Such features help to make VoLTE call reliability, quality and efficiency significantly higher than with OTT VoIP applications.